Pqhor
I'd say try what you got. It will harrier and hover fine. If you don't like it, it only takes what 20-30 minutes tops to put a longer fuse on. Personally I like to have two Pqhors. One has a 32" wing and fuse and does great 3-D stuff. My big one with 36" wing and fuse is by far waaaay more stable in harrier, hover, and t-roll.
JCaste- Thanks for the compliments. I'm not sure what your asking about the hovering in a circle thing? Also I'm not sure what prop would be best on a 40fx. Hope you like have fun with yours.
Jason